Some components, for example ceramic varistors for protecting electrical networks and installations against overvoltage and overcurrent, require contact-connection elements for external contact-connection which afford a high current-carrying capacity. For this purpose, an outer metallisation in the form of a thin metallic layer (e.g., silver) can be applied with a homogeneous thickness on the component body, for example a ceramic varistor. For external contact-connection, via which the supply of the component body is effected, for example contact metal sheets (e.g., composed of sheet copper) are soldered onto the metallized areas of the component body, such that they completely or partly cover the metallized areas.
There are various geometry variants for the contact-connection elements for external contact-connection which pursue the approach that the connection metal sheet for external contact-connection covers the metallized areas approximately over the whole area. A disadvantage is that large contact areas bring about high thermomechanical stresses after the connection metal sheet has been soldered on, which potentially lead to cracking in the ceramic body and as a further consequence potentially to the failure of the component. Further disadvantages are that the soldering quality is difficult to evaluate and some specification or customer requirements can be difficult to implement with metal sheets soldered on approximately over the whole area.
Another approach involves rings or strips being soldered on, which partly cover the metallization areas, but the form of which is not optimal with regard to the current-carrying capacity. Here the disadvantages are inhomogeneous current density distributions bring about local excessive temperature increases in the metallization layer. As a result, either the current-carrying capacity of the component decreases or it is necessary to use thick metallization layers, which increase use of material and costs.